The present disclosure relates generally to operations performed and equipment utilized in conjunction with wellbore operations and, in particular, to moving tubular members in and out of a well.
Coiled tubing, jointed pipe, or other similar tubular members generally include cylindrical tubing made of metal or composite. The tubular members may be introduced into an oil or gas wellbore or pipeline through wellhead control equipment to perform various tasks during the exploration, drilling, production, and workover of the well/pipeline. For example, coiled tubing may be inserted by a coiled tubing injector apparatus. Such injectors generally incorporate a pair of opposed endless drive chains which are arranged in a common plane. The drive chains are often referred to as gripper chains because each chain has multiple gripper blocks attached along the chain for handling the tubing as it passes through the injector.
The opposed gripper chains are generally provided with a predetermined amount of slack which allows the gripper chains to be biased against the tubing as the tubing moves into and out of the wellbore. This biasing is accomplished with an endless roller chain disposed inside each gripper chain. Typically, each roller chain engages sprockets rotatably mounted on a respective linear beam. The linear beams may be moved toward one another so that each roller chain is moved against its corresponding gripper chain such that the tubing facing portion of the gripper chain is moved toward the tubing so that the gripper blocks can engage the tubing and move it through the apparatus. When the gripper chains are in motion, the gripper blocks will engage the tubing along a working length of the linear beam. Each gripper chain has a gripper block that comes into contact with the tubing at the top of the working length of the linear beam as another gripper block on the same gripper chain breaks contact with the tubing at the bottom of the working length of the linear beam. This continues as the gripper chains force the tubing into or out of the wellbore.
Tubular members introduced into the wellbore may not have a constant cross section. For example, a variety of outside diameters of tubing may be used in a particular drilling operation, or a pipe joint or connector between two reels of coiled tubing may result in a change in outside diameter of the tubular member directed into the wellbore through the injector.
While embodiments of this disclosure have been depicted and described and are defined by reference to exemplary embodiments of the disclosure, such references do not imply a limitation on the disclosure, and no such limitation is to be inferred. The subject matter disclosed is capable of considerable modification, alteration, and equivalents in form and function, as will occur to those skilled in the pertinent art and having the benefit of this disclosure. The depicted and described embodiments of this disclosure are examples only, and not exhaustive of the scope of the disclosure.